Relationship Between Insect Damage and Chlorophyll Content in Mediterranean Oak Species

Considering that the damage caused by phytophagous insects can alter the chlorophyll content of plants, we established the hypothesis that variations in chlorophyll concentration could be applied to assess stress caused by these kind of harmful agents. In this paper, relationship between insect damage and the chlorophyll content of sclerophyllous oak species (Quercus suber and Q. ilex) is investigated. The survey was carried out in Hornachuelos Natural Park (southern Iberian Peninsula). For each plant species, a comparative study of chlorophyll concentration on healthy leaves was performed among a control group of harmless trees and other groups affected by one of the following damaging insects: woodborers, chewing and gall-formers. Results relative to Q. ilex indicated that only damage by gall-formers had a significant effect on average chlorophyll content of healthy leaves. As regard Q. suber, differences in chlorophyll content were only significant when injuries were caused by the woodborer Coraebus florentinus. In conclusion, insect damage could influence the chlorophyll content of the holm and cork oaks, but the effect varies depending on the plant species and the type of harmful agent.